Electromechanical arrangement controlling a movable part in at least two directions



April 1963 E. ASCOLI 87,772

ELECTROMECHANICAL ARRANGEMENT CONTROLLING A MOVABLE PART IN AT LEAST TWO DIRECTIONS Filed April 27, 1960 MIIIENTOIE Exvz 0 #5 e04 rte ite

Filed Apr. 27, 1969, Ser. No. 24,985 Claims priority, application Switzerland May 29, 1959 12 Claims. (Cl. 346-140) Numerous electromechanical arrangements are already known which allow controlling the shifting of a movable part by modification in an electric current. The electrodynarnic arrangements of this type, which are the more generally known, such as loudspeakers, pick-up, measuring instruments and the like include generally a permanent magnetic field in which a movable winding fed with modulated current is adapted to move. Thus, by reason of the structure of such apparatus, the magnetic force or torque acting on the movable winding perpendicularly to the plane formed by the vectors defining the field and the current will be modulated along this single perpendicular direction. Obviously, the magnetic force or torque applied or the shifting or angular deflection of the winding can correspond only to a single modulated variable, or reversely, the modulated current collected can correspond only to a single component of the displacement producing it.

In certain technical fields, it may the of interest to control a movable member so as .to impart to it movements in two different directions. Thus, in the typewriter described in the French Patent No. 1,244,794, it is necessary to shift a tracing member or stylus in a plane or even in space. If it is desired to impart the necessary movements to said tracing member or stylus by means of conventional electromechanical arrangements, it will be therefore necessary to provide two or even three windings fed each by a modulating control current. Such a solution cuts out substantially the advantage of the light weight inherent to the movable elements of electrodynamic arrangements and this means that, taking into account the frequencies and the amplitudes required for a proper operation of the tracing member, the mass of the moving element thus designed would hardly be consistent in practies with the forces, currents or sizes to be considered.

My invention has for its object to cut out said drawback and it covers an electromagnetic control system for a part adapted to move at least in two directions. According to my invention, the movable part is controlled by a winding lying in the gap formed between two rnemers made of ferromagnetic material and arranged inside one another, while at least two further windings are carried by at least one of said members, each of said further windings being arranged so as to be capable of generating a magnetic field in a section only of the gap, the magnetic fields having predetermined direct-ions.

l have illustrated, by way of example, in the accompanying drawings a preferred embodiment of my invention. In said drawings:

FIG. 1 is an elevation sectional view of said embodiment through line Il of FIG. 2.

FIG. 2 is a cross-section through line Il-II of FIG. 1.

The embodiment illustrated forms a tracing arrangement adapted to equip a typewriter of which FIG. 1 shows the platen 1 round which the paper is wound in the conventional manner. The actual arrangement includes a flange 2 of soft iron carrying an outer magnetic armature 4 and an inner magnetic armature 5, both armatures being secured to said flange by screws 3. These two armatures 4 and 5 constituted by laminatio-ns are arranged co- Patented Apr. 30, 1953 axially and are provided each with four pole-pieces 6a and 6b, respectively, the two pole-pieces on the two armatures facing each other pairwise and extending along two diameters perpendicular to each other x and y. The pole-pieces are bounded by spherical surfaces having a common center at 0 and they form four narrow gaps 7 between the two armatures. Four windings 22a, 22b, 22c, 22d surround the corresponding pole-pieces of the armature 5 after the manner of a four-pole alternator rotor. A frusto-conical cover 8 secured laterally to the outer armature 4 through the above-mentioned screws 3 carries at its outer end an extension formed by yielding conical fiuidtight bellows 9, the outer end of which is secured to a tubular rod 10 carrying near its other end the moving element of the electromagnetic system. Said movable element is constituted by a support 11, in the shape of a spherical annulus having as a center 0, extending through the gaps 7 and carrying at its periphery a single winding 12; on the other hand, the tubular rod forms at its outer end a tracing point 13 in contact with the paper on the typewriter platen during typewriting. The tracing point draws the desired line on the paper with the ink fed to it through the yielding pipe l openinginto the opposite end 14 of the tubular red It The moving element includes furthermore a ball 16 the center of which lies at ti and through which the tube it) extends to which it is secured and, lastly, connecting and stiffening members for the moving element are provided, as constituted by the disc 17 and the ribs or stays 18 fitted between the tubular rod it) and the annular support 11.

The ball id is adapted to rock or pivot freely in all directions without any clearance inside the cylindrical bore formed in a ring 19 of a very hard material, say sapphire. Two rubber washers 2d are urged against the opposite sides of the ring 19 by the flange 2 and the cooperating plate 21 secured thereto by the above mentioned screws 3 and said washers through which the tubular rod 10 passes limit the movements of the ring and consequently of the rod 10 in all directions along the three coordinates x, y and 1 while they provide an elastic return movement for the moving element.

The operation of the arrangement is as follows: the winding 12 is fed "with D.C. of a constant current intensity flowing in the direction of the arrow 23 for instance. When the stationary windings 22a and 22c corresponding to the direction x are fed with current in a direction such that the magnetic field passes through the two corresponding gaps 7 as illustrated by the arrows 24 and 25, the movable element is subjected to a torque adapted to shift the tracing point or stylus 13 on the rod 10 in a corresponding direction, until it reaches a position of equilibrium which depends on the characteristic properties of the elastic washers 2t and on the intensity of the field produced. If the current in the two windings is reversed, the direction of the torque will change since the current flowing through the winding 12 remains constant. Thus, the modulation of the current in the windings of the x axis produces a modulation of the movement of the stylus in said direction x.

Similar results are obtained in the direction y, indeendently of the movement in the direction x.

It is thus possible to control any desired movement of the end of the stylus. Said stylus would move over a spherical surface if the axial elasticity of the washers 20 did not urge the stylus permanently against the cylindrical surface of the paper sheet.

As a matter of fact, the movements of the stylus 13 along the direction x or y are very small with reference to the radii of curvature of the said spherical and cylindrical surfaces so that the spacing between the stylus and the paper is absorbed by very small movements in the direction 2, which latter movements are allowed by the axial elasticity of the washers 20.

The movements along the axis z are obtained as follows: the four stationary windings are fed in an identical manner with a current, the direction of which is such, if no modulation in the direction x or y is applied, that the magnetic fields in the four gaps are all directed towards the center 0, or else, away from said center 0. The magnetic circuit closes then through the flange 2 and the winding 12 is subjected to an axial force urging the stylus 13 away or towards the paper sheet according to the direction of the current. The magnitude of said movement in either direction depends on the intensity of the field and on the elastic properties of the Washers 20.

Obviously, the modulating current in the direction z may be superposed over the modulation of the currents in the directions x and y in the different stationary windings without any interference of any of the three variable x, y, z With the other variable. This is ascribable to the fact that the modulating current in the direction 2 for instance in each of the two x windings produces on the moving element two equal forces, facing the same direction in parallelism with the axis z, but the points of application of which are diametrically opposed with reference to the center so that they do not act in the direction x. The same is the case for the windings corresponding to y.

In the above description of the operation, it has been assumed for sake of clarity and of simplicity that the current flowing through the windings on the moving element was constituted by DC. of a constant value without any modulation. It is however possible to act on its intensity in order to obtain an amplification or a reduction which is proportional to the simultaneous displacements in the direction of x and y for instance with a view to obtaining a predetermined size of character, or to obtaining certain letters the shape of which is similar as a capital and as a small letter such as C, O, S, U, V, W, Z, with the same modulating signals along the axes x and y.

It should also be remarked that, starting from a same record supplying modulating currents for the obtention of a straight writing, it is an easy matter to obtain a sloping writing with the axis of the y sloping towards the right or towards the left by a predetermined angle, while the axis of the x remains horizontal, this being provided by adding to or subtracting from the modulated x signal,

a signal proportional to 32 without any modification of the y signal. The x signal is thus transformed into X=x+Ky, K being the desired slope.

Lastly, it is easy to imagine variable and independent amplifications of the two signals adapted to control the movements along the axis x and y, so as to modify as desired the ratio between the breadth and the height of the characters independently of the slope and size in one di rection.

The DC. of a constant value feeding the movable winding may be replaced by an alternating current provided that at each moment the product i i of the intensities passing through the movable winding and the stationary windings is proportional to the desired modulation. As a matter of fact, except for structural unvarying parameters, the force is proportional, if the non-linearity of H =f(B) is neglected, to said product:

F being the force in grams, n the number of convolutions fed with the current i H the intensity of the field in Gauss, L the length in centimeters fed by the current i in the field H and i; and i the currents in amperes.

The control through an alternating current may be obtained for instance as follows: assuming i =A sin wt and it is readily apparent that the mean value of the product i i follows sinusoidally the phase modulations of on between and reaches for said extreme values a negative or positive maximum and is equal to zero when 04:0. It is possible to obtain substantial linearity between the product i i and a by limiting operation to a range extending between limits within the extremes It is apparent from this example that the desired result may be reached by feeding the movable winding with an unvarying alternating current and by modulating the phase of the current passing through the stationary windings which current is of the same frequency, but with a lead of 1r/2. In this case, the frequency of the alternating currents should be much higher than the actual resonant frequency of the moving element.

I claim:

1. An electromechanical control device for controlling the movement of a movable part in at least two dimensional directions, comprising, in combination, a first ferromagnetic member, a second ferromagnetic member positioned within and spaced from said first ferromagnetic member, whereby a gap is formed therebetween, a first energizable winding means for producing a first magnetic field in a first predetermined dimensional direction within said gap between said ferromagnetic members, a second energizable winding means for producing a second magnetic field in a second predetermined dimensional direction within said gap between said ferromagnetic members, each of said energizable winding means being mounted on one of said ferromagnetic members, and a third energizable winding means for moving the movable part, said third energizable means being movable simultaneously in at least said two dimensional directions within said gap.

2. An electromechanical control device for controlling the movement of a movable part in at least two dimensional directions, comprising, in combination, a first -ferromagnetic member, a second ferromagnetic member positioned within and spaced from said first ferromagnetic member, said members being coaxially positioned with respect to each other, one member including four symmetrically positioned pole pieces, each of said pole pieces of said member facing said other member, whereby a gap including four polar symmetrically positioned elementary gaps is formed, a first energizable winding means for producing a first magnetic field in a first predetermined dimensional direction in one of said elementary gaps, a second energizable winding means for producing a second magnetic field in a second predetermined dimensional direction in another of said elementuy gaps, each of said energizable winding means being mounted on one of said ferromagnetic members, and a third energizable winding means for moving the movable part, said third energizable winding means extending through said four elementary gaps of said gap and being movable simultaneously in at least said two dimensional directions within said gap.

3. An electromechanical control device for controlling the movement of a movable part in at least two dimensional directions, comprising, in combination, a first ferromagnetic member, a second ferromagnetic member positioned within and spaced from said first ferromagnetic member, said members being coaxially positioned with respect to each other, one member including four symmetrically positioned pole pieces, each of said pole pieces of said member facing the other member, whereby a gap including four polar symmetrically positioned elementary gaps is formed, each of said pole pieces having positioned therearound a separate energizable winding means for producing a magnetic field in a predetermined dimensional direction in each of said elementary gaps, and an additional energizable winding means for moving the movable part, said additional energizable winding means extending through said four elementary gaps and being movable simultaneously in at least two dimensional directions within said gap.

4-. The device of claim 3 wherein said additional energizable winding means conforms to the shape of a spherical annulus.

5. An electromechanical control device for controlling the movement of a movable part in at least two dimensional directions, comprising, in combination, a first ferromagnetic member, a second ferromagnetic member positioned within and spaced from said first ferromagnetic member, whereby a gap is formed thcrebetween, said second ferromagnetic member being provided with a central recess, means pivotally mounted within said recess and carrying the movable part for moving the movable part in at least two dimensional directions within said recess, a ferromagnetic flange means for securely holding said ferromagnetic members, a first energizable winding means for producing a first magnetic field in a first predetermined dimensional direction within said gap between said ferromagnetic members, a second energizable winding means for producing a second magnetic field in a second predetermined dimensional direction within said gap between said ferromagnetic members, each of said energizable winding means :being mounted on one of said ferromagnetic members, and a third energizable winding means for moving the movable part, said third energizable means being operatively associated with the movable part and being movable simultaneously in at least two dimensional directions within said gap.

6. The device of claim 5 wherein said means pivotally mounted within said recess comprise a ball-shaped member rigid with respect to said movable part, a ring provided with a cylindrical bore in which said ball-shaped member is positioned, said ring being revolvably positioned in said recess, and elastic means for holding said ring in position in said recess, said elastic means engaging said ball-shaped member and being secured to said second ferromagnetic member.

7. The device of claim 4 including ferromagnetic flange means for securely holding said ferromagnetic members, said second ferromagnetic member being provided with a central recess, a ring provided with a cylindrical bore, said ring being revolvably positioned in said recess, a ballshaped member being pivotally positioned in said recess, said ball-shaped member being rigid with respect to said movable part, and elastic means for holding said ring in position in said recess, said elastic means engaging said ball-shaped member and being secured to said second ferromagnetic member.

8. In combination, a stylus movable in at least two dimensional directions and an electromechanical control means for controlling the movement of said stylus in said two dimensional directions, said means including a first ferromagnetic member and a second ferromagnetic member positioned therewithin and spaced from said first ferromagnetic member, whereby a gap is formed therebetween, a first energizable winding means for producing a first magnetic field in a first predetermined dimensional direction within said gap, a second energizable winding means for producing a second magnetic field in a second predetermined dimensional direction within said gap, each of said energizable winding means being mounted on one of said ferromagnetic members, means for feeding ink into said stylus, and a third energizable winding means for moving said stylus, said third energizable winding means being movable simultaneously in at least said two dimensional directions within said gap, said stylus and said feeding means therefor being operatively associated with said third energizable winding means within said electrical control means.

9. In combination, a stylus movable in at least two dimensional directions and an electromechanical control device for controlling the movement of said stylus in said two dimensional directions, said control device comprising a first ferromagnetic member and a second ferromagnetic member positioned therewithin and spaced from said first ferromagnetic member, said members being coaxially positioned with respect to each other, one member including four symmetrically positioned pole pieces, each of said pole pieces of said member facing the other member, whereby a gap including four polar symmetrically positioned elementary gaps is formed, each of said pole pieces having positioned therearound a separate energizable winding means for producing a magnetic field in a predetermined dimensional direction in each of said elementary gaps, ferromagnetic flange means for securely holding said ferromagnetic members, said second ferromagnetic member being provided with a central recess, a ring member provided with a cylindrical bore, said ring member being revolvably positioned in said recess, a ballshaped member pivotaliy mounted in said cylindrical bore, a tubular rod member rigid with and coaxially positioned with respect to said ball-shaped member, means for feeding ink into the inner end of said tubular member, said stylus being mounted on said tubular rod member at the outer end of said tubular rod member, elastic means for holding said ring at the ring side walls in position in said recess, said elastic means engaging said ball-shaped member in said ring and being secured to said second ferromagnetic member, an additional energizable winding means for moving the stylus, said additional energizable winding means extending through said four elementary gaps and being movable simultaneously in at least two dimensional directions within said gap, yielding cover means for enclosing said tubular rod, said yielding cover means being secured to said rod at the portion thereof immediately to the rear of said stylus and also to said first ferromagnetic member.

10. The device of claim 4 including means for feeding each of said windings positioned around each of said pole pieces with modulated alternating currents, thereby to produce a magnetic field of a predetermined dimensional direction in each of said elementary gaps, and means for feeding said additional energizable winding means with a constant direct current.

11. The device of claim 4, including means for feeding said additional energizable winding means with alternating current at a predetermined frequency and means for feeding each of said windings positioned around each of said pole pieces with modulated alternating currents having a phase lead of 1r/2 with reference to the current feeding said additional energizable winding means.

12. The device of claim 8 wherein said two ferromagnetic members are coaxially positioned with respect to each other, and including means for feeding said additional energizable winding means with alternating current at a predetermined frequency and means for feeding said windings with modulated alternating currents along the axes of said ferromagnetic members and in two perpendicular dimensional directions with respect to said axes.

Thomas June 11, 1935 Dreyfus Feb. 15, 1955 

1. AN ELECTROMECHANICAL CONTROL DEVICE FOR CONTROLLING THE MOVEMENT OF A MOVABLE PART IN AT LEAST TWO DIMENSIONAL DIRECTIONS, COMPRISING, IN COMBINATION, A FIRST FERROMAGNETIC MEMBER, A SECOND FERROMAGNETIC MEMBER POSITIONED WITHIN AND SPACED FROM SAID FIRST FERROMAGNETIC MEMBER, WHEREBY A GAP IS FORMED THEREBETWEEN, A FIRST ENERGIZABLE WINDING MEANS FOR PRODUCING A FIRST MAGNETIC FIELD IN A FIRST PREDETERMINED DIMENSIONAL DIRECTION WITHIN SAID GAP BETWEEN SAID FERROMAGNETIC MEMBERS, A SECOND ENERGIZABLE WINDING MEANS FOR PRODUCING A SECOND MAGNETIC FIELD IN A SECOND PREDETERMINED DIMENSIONAL DIRECTION WITHIN SAID GAP BETWEEN SAID FERROMAGNETIC MEMBERS, EACH OF SAID ENERGIZABLE WINDING MEANS BEING MOUNTED ON ONE OF SAID FERROMAGNETIC MEMBERS, AND A THIRD ENERGIZABLE WINDING MEANS FOR MOVING THE MOVABLE PART, SAID THIRD ENERGIZABLE MEANS BEING MOVABLE SIMULTANEOUSLY IN AT LEAST SAID TWO DIMENSIONAL DIRECTIONS WITHIN SAID GAP. 